Mirror and Prism Degradation in old SLRS

My question is this: is it possible to re-silver old pentaprisms? I've seen people get good results re-silvering old mirrors, but that is a flat plane of glass. Further is the quality that is fine for a mirror good enough for a camera pentaprism?

I ask because I've noted degradation of prisms on several Edixas and Prakticas I have, which results in a hazy, hard to focus image. When a good prism was substituted the finder image became sharp again, so I know it is not a problem with the focus screen or eyepiece. I also have one Praktica which has acquired an odd greenish tint to the reflex mirror which causes a similar issue but also makes the viewfinder image much dimmer.

On a couple of the Edixas there appeared to be a fungus growing on the prisms:

These prisms all gave hazy viewfinder images.

So how about it? Can prisms be re-silvered? Is it worth the bother? (ie. will the quality be high enough for use in a camera?)

I'm pretty sure all or almost all of these were "silvered" by vacuum depositing aluminium onto the surfaces. I helped a friend do this on a telescope mirror, and it's doable at home if you have the equipment - a vacuum pump, big enough bell jar, and a high current power source to evaporate the aluminium. Look around the DIY astronomy websites.

Yes you can get mirrors and presumably pentaprsims re-silvered. Vacuum Coatings Ltd in London are good, I've recently had a new front surface mirror made for a pre WWII quater plate SLR, relatively inxepensive at £16 inc postage.

You'd need to remove the old coating, this is usually done with acid which doesn't affect the glass itself, then after cleaning the item is re-silvered, usually these days it's an aluminium layer but just as good if not better than silver. The two surfaces entry/exit would need to be masked off.

Once you got it back you'd need to paint the coated srfaces of prism here I've not thought what would be ideal yet.

I didn't have time to post a link last night to Vacuum Coatings Ltd / Csientific Mirrors. They do list camera prism restoration. I'm going to get a new front surface mirror for a sceond SLR shortly - a pre WWII Ensign Speed Roll film reflex and if I get time may get them to refurbish the mirror and prism from an old Exa II.

You'd need to check whether the'll strip a prism before re-silvering, they will strip & clean mirrors although I had them make a new one for my Ruby Reflex. Their prices are very reasonable and they are extremely helpful.